In a first type of design, proposals have been made to confer the function of supporting the mechanism to the revolver frame alone. In this case, the revolver frame constituting the master component of the gun is machined so that it can itself support the various moving parts: said frame then constitutes a housing containing all the important moving parts and withstanding the various forces that occur on firing, with said housing being closed by a simple lid constituting a cover plate.
Such a design manufacture, the frame constitutes a part which is expensive because of the various different machining operations which must be performed, and in particular the difficulties of machining various passages which are difficult of access and therefore require special tools. It must be understood that precision machining is essential for proper operation of the mechanism, in particular where it determines the positions of the various cross pivots or pins of the mechanism and thus the associated distances therebetween.
In addition, it is difficult to adjust the mechanism because of the poor accessibility of the various parts of said mechanism.
Finally, the mechanism is constituted by individual parts mounted one after the other on the frame on the gun, rather than in the form of functional subassemblies capable of being separately adjusted and/or replaced: as a result there is very little room for interchangability in the full set of moving parts. U.S. Pat. No. 3,548,530 may be mentioned as illustrating a revolver frame having a mechanism receiving housing which is closed by a cover plate. This cover plate serves as a lid and does not support the gun mechanism; said plate merely has two bores serving as bearings for the hammer pivot and the trigger pivot, in entirely conventional manner, with the special feature of the mechaism described lying in the hammer and the trigger being made by casting under pressure and by the associated pivots being force-fitted.
In a second type of design, proposals have been made to collect some of the parts of the mechanism together by mounting them on the trigger guard of the revolver, said guard then constituting a mechanism carrying add-on part. Such a design is illustrated, for example, in U.S. Pat. No. 3,654,720. The guard receives the trigger and various parts of the mechanism (essentially the cylinder pawl and the striker plate lever).
Although this design may simplify the operations of assembling or replacing the functional subassembly carried by the guard, it is even more difficult with respect to the degree of machining accuracy required: in particular the important distance between the hammer and the trigger requires very high precision. Indeed, this design is even less satisfactory when it comes to adjustment operations because of the trigger guard plate being mounted blind.
Proposals have been made to improve this design somewhat by defining the distance between the hammer and the trigger on a single part, for example as shown in U.S. Pat. No. 4,213,263. However, in spite of the improved accuracy thus obtained, this design does nothing to reduce the difficulty of machining, and it does not make it possible to check the relationship between the mechanism and the cylinder. Naturally, the same drawbacks as mentioned above still apply with respect to difficulty of performing adjustment.
Thus, this second type of design with a partial subassembly mounted on an add-on trigger guard necessarily requires very high machining accuracy for mounting on the frame, and is hardly satisfactory for performing maintenance operations: in any event adjustment remains difficult, in particular since the operation of the mechanism cannot be seen when the gun is assembled (indeed, technicians are often obliged to make additional openings in sample pieces in order to be able to observe the mechanism).
A design has also been proposed which lies halfway between the two above-mentioned designs, having a one-piece grip-and-trigger-guard assembly which serves as a mechanism carrier. This is illustrated, for example, in U.S. Pat. No. 3,810,326 or in French Pat. No. 2,487,062.
The assembly described in U.S. Pat. No. 3,810,326 is more satisfactory than that mentioned above, as described in U.S. Pat. No. 3,654,720, insofar as means are provided for integrating the members acting as a cylinder latch or stop (part reference number 18) in with the assemblies for driving the hammer and the trigger. However, the grip-and-guard assembly must be capable of being machined with great accuracy and merely by observing the structure of this assembly with its central channel for receiving the various parts of the mechanism it will be understood that the operations of machining this assembly and the operations of adjusting the mechanism (which can be reached only through the central channel that does not have any side openings) are difficult.
It should also be observed that this last-mentioned halfway design suffers from an additional drawback which may have major consequences in operation, said drawback concerning the assembly of the cylinder pawl, i.e. the index level which rotates the cylinder (reference 22 in U.S. Pat. No. 3,810,326). The cinylinder pawl is guided solely by the adjacent region of the frame by being received in a groove therein: as a result, if the pawl is to be properly positioned transversely, the frame-forming grip-and-guard assembly must be very accurately machined, which is difficult to do because of the very structure of said assembly. In operation, the consequence of faulty transverse positioning of the cylinder pawl is to cause the cylinder to rotate either too much or else too little.
Additional items of the state of the art that may be mentioned include: British Pat. No. 731,093, and U.S. Pats. Nos. 4,641,449; 3,024,559; 2,927,390; 2,640,396, and 2,659,172. It may be observed that the last-mentioned patent concerns a child's toy (a pistol for use with a strip of caps, with the pivots for the hammer and the trigger being mounted on a frame which also constitutes the grip).
The object of the invention is to provide a support device for a revolver mechanism which is more effective than the above-described prior devices, and in particular which facilitates the operations of manufacture and assembly, thereby also making it possible to reduce manufacturing costs.
Another object of the invention is to improve accessibility for adjustment and/or inspection and/or assembly, and in particular to make it possible to automate assembly, and also to make it possible to interchange an entire set of moving parts.
Another object of the invention is to provide a support device which facilitates proper transverse positioning of various moving parts of the mechanism, and in particular of the cylinder pawl, by virtue of easily-obtained accurate lateral guidance.